Dynamo-electric machine for maintaining a constant electromotive force under variations of speed.



Dunno 213101 310 24 MW. W. MAGKIE. AGHINE FORMAINTAINING A CONSTANT BLEGTROMOTIVE FORGE UNDER VARIATIONS OF SPEED.

APPLICATION FILED AUG. 24, 1006.

Patented Jan. 24,1911.

UNITED STAJIQES l f klflilllbilt W'KLLIAM WALBAETK MAGKIE, SEALING;

UNDER Specification of Letters Patent.

Patented. i r

Application filed August 24%, 1906. Serial No. 831,886.

To all whom it conic;

lie it known that l, Mirr'rri'mv \iVILLL l i iineiinn Mannie, a. subject of the King.

. tftreat Britain. and lrclan rcsidii at Slimlin in the county of Middlesex, .lng

i sponiiling to a desired normal l l. M. F. or

voltai fbe caused to-maintain that voltageronsunt within a very small *ariation, altl'iough the speed may be varied to a considerable extent above such predetermined or normal speed, at which the required voltage is produced, thereby specially adapting such machine to be driven from a ailway vehicle for train lighting.

For the purpose of this invention, a multipolar dynamo machine used wherein all the poles are provided with a shunt u'indlug and some onlyof them are provided with a (leuiagnetizing or regulating winding (hereinzufter referred to as the demagnetizing Winding) which is controlled by 'an accumulator in such manner that the. voltage of the dynamo maintained practically constant even when the dynamo running above the normal speed at which the rcquired normal voltage is produced, the dynamo at lower speeds than the normal being automatically put out" of action.

In carrying out the invention, there are con'iliiined with a multipolar shunt around dynamo electric machine, a den agnetizing Winding arranged on some only of its poles,

means. for opening the circuit oi? theiiiachine when its speed falls below that necessary for supplying the required voltage, and an accumulator (hereinafter called for distinction the working accumulator) which is connected in series with the dcn'iagnetizing Winding across the brushes of the machme and also it. may be to a work CllCtllt to which the demagnctizing windingwould also be then connected. The arrangement is such that under normal conditions oi": speed, the d name will generate the ii'equireddd. M. i which 111" be equal, or no ""ly so, to than that oil the wet n'iulator. in the latter thel l. l germ erated maybe sullicicnt tocharggo a second accumulator arranged in a circuit direct across generated may be suli'icicnt to charge a. sccond"accumulate arranged in a circuit direct the brushes oi the machine and designed to be interclmnged with the other battery to as the working battery. in either case the deinagnctizing Winding is made of such resistance that, at the normal speed and voltage o1 the dynamo, only a. very small current will low through it so that the ma gnetic poles on which it is arranged will be practically unaffected by such current, the v ltage drop in the Winding, at the said normal viiiltagc, together with the ll. lift. F. of the Working accumulator, being practically equal to the normal voltage. Under such normal conditions, it the working ac cumulator and demagi'ictizing Winding be connected at a point between them to a,

work circuit, any current. required for such Work circuit will be mamly su p plied by the Working fl'tffiilllllllfilfllw Upon the speechand conseqnei'itly the voltage of the machine, rising above the nmrnial, the current tlowing through the dcmagnetiziug Winding will be increased and act to more or less demagnctize the poles HPGD'Wl'llOll it is wound, in such manner that the voltage of the machino will be prevented'iirom rising, except to a small permissible extent, say half a volt, above the normal voltage, while upon the speed of the machine falling below the norn'ial, that is to say to an amount insutlicient' to charge the second accumulator or.

connected directly across the brushes oi: the machine, if a second accun'iulator-be used the circuit of the machine will be automatically opened by the means provided for that purpose, the Working accumulator in the latter case being then Wholly relied upon for siuiplying any current required for the Work circuit.

The accompanying drawings show examples of various methods or means whereby the system of demagnetization of some of the magnet poles of a dynamo electric ma chine, as above set forth, is utilized to'cilect the required governing action upon variation oi? speed of the machine from the normal speed, Fiejures 1 and l being diagrams of {our pole. lunt Wound generators and F and i r diagrams of sis: polo zors showing dillfereni;

Bil

l), D is connected to one bru embodiments ofthe invention. 1g. 3 is a diagram showing the circuitconnections for a generator such as is shown in Fig l.

The main shunt winding may be arranged on the poles of the machine in any well known way, the shunt winding. applied to the four alternate magnet poles is N 2.2 in Fig. 1, being shown by a thin line and marked a o '0. The demagnetizingwinding, shown. for distinction as a thick line, wound upon half the number of pairs of poles, as represented at D D In the case of a six pole machine, as shown in Fig. :2, four of the six poles may be wound with the demagnetizing winding D l), leaving the remaining two poles wound with the shunt winding a 7) a only.

The armature c employed in each of the arrangements showndn Figs. 1 and E3, is an ordinary series or wave wound arimitureq and the shunt winding (L c connected across the brushes a, Z in the usual manner. One end of the demagnclizing 'wimling sh, viz. a, the other end of such winding being connected to the circuit terminal E. The n'i thod of governing by the aid. oi. the said demagnetizing winding D D for maintaining a practically constant E. M. i bbctween the brushes of the-machine is shown in. Fig. in this example, which is suitable for train light.- ing, a set of electric accumulator cells A and electric lamps H are connected between the circuit terminal E and the second brush 7) of the armature e, and another set of electric y accumulator cells B is connected directly across the two brushes a Z) of the machine.

The set of accumulator cells It designed to give an E. M. E. of the predetermined required amount "for working the lamps H, and a counter E. M. F. necessary to regulate the demagnetizing winding D D- which is made of such dimensions that only a small current will flow through it at. normal voltage so that the winding will be practically inoperative upon the poles of the machine upon which it is placed, and that the voltage drop in the said. winding at such normal voltage, plus the voltage of the of no cumulator cells A, will practically be equal to the normal voltage of the machine, as hereinbefore set forth. The set of accumulator cells B is designed to give the same E? M. F. on discharge as the set A and being connected across the brushes c Z2 can be charged by the machine in readiness for use in lieu of the set A when these have been discharged. To enable the cells B to he charged, the normal voltage of the machine generated at a given predetermined speed, must therefore be greater than that of the cells A which are being used for-regulating and current supply purposes. it device of any known or suitable kind ma y be provided for causing the two sets of accumulators to change places at suitable intervals, the set that is, for the time being, between the icrminal E and brush 7) not being changed over until after the other set has been connected across such terminal E and brush Z). For this purpose, the terminal E may be connected to one segmental contact f oi a hattery interclulnging switch while the brush a is connected to a second segmental contact f ofthe said switch, the co-acting brushes g, being respectively connected to the positive pole of the accumulator A and the positive pole of the accumulator B. The negative poles of the two accumulators 1 and B are arranged to be connected to the negative brush 5 of the machine through a second switch or automatic cut-out comprising a. fixed contact it connected to the brush 7) and a movable contact h controlled by a centrifugal speed governor is driven from the shaft or axle used for rotating the armature of: the dynamo machine. The said out out serves to open the dynamo circuit when the speed of the armature falls below that necessary "for supplying the normal voltage i'ieccssary for charging the secondary battery connected across the brushes of the machine. By partial rotation of the contacts f, f of the interchanging switch when the machine is running at or above its normal speed, con- 9 tact y. will be connected to contact and contact to contact f so as to respectively connect the accumulator A across the brushes a, Z) and the accumulator B between the terminal E and brush 7), thus interchangiug the two accumulators. The brushes (1-, D can of course be connected to any additional work circuit, if desired.

The governing action of the arrangcim-nt is as follows :--\Vhcn the machine is running at a certain predetermined speed, its E. M. F. will be the normal'E. M. F. required to commence charging the set of accumulator cells B across the brushes (1 b, and which it is the object of the invention to maintain practically constant at speeds above the said predetermined speed, the resistance of the demagnetizing winding D D being so proportioned, as hereinbefore stated, that at this time very little current will flow through such winding and the second set of accumulutoiwcells A connected in series with it across the brushes a b. The field magnet poles and the armature of the machine will then act as in an ordinary shunt wound machine and charge the set of accumulator cells B, the accumulator A. meanwhile acting, if necessary, to supply the lamps H with current independently of the dynamo machine, and also to oppose a counter E. M. l. to the direct E. M. F. in the demagnctizing winding so that very little current will flow through the said winding at this time to the work circuit. When the speed. of the machine increases beyond the predetermined demagnetization, or a counter E. M. F. may

- even be produced in opposition to the E. M.

generated in those conductors on the armature that are, at the moment, passing under the magnet poles that have not been demagnetizcd. Atthis time the larger current flowing through the demagnetizing winding D D is utilized to charge the accumulator A, or to work the lamps H. hen the speed of the machine falls below the pre determined normal. speed, the dynamo circuit through the seconiilary battery B between the brushes 5; and Z1 will, as usual, be autonmtically opened by the speed governor Z2, such circuit being again automatically closed vhen the speed attains the normal value.

ny the means described a-practically 0011- I stant E. M. F. can. be maintained between the brushes a and b which, as before stated,

can be connected to the work circuit includ' mg the set of accun'iulator cells B or any" other electric translating devices. The use, as set forth, of an electric accumulator, such as A, in series with a demagnetizing wind ing for maintaining a practically constant- .l. M. F. in a dynamo-electric machine not.- withstanding variation of speed abov' the normal, in conjunction with another similar accumulator arrai'iged to be charged by the machine while the other is in use and to be substituted therefor when discharged, constitutes an important feature of this invention. I

By placing the demagnetizing winding on some only of the poles of the machine, as described,- partof the magnetic field of the dynamo will he unatl'ected so that con'in'iutation can take place in a held of practically constant strength and so avoid anysparking troubles. For this reason, the field of the poles to which the demagnetizing winding is applied can not only be weakened but even reversed, in which case, part of the armature will act as a generator and part as a motor, thereby enabling the E. M. F. of the machine to be maintained practically constant within considerable ranges of speed variation above the normal speed.

Fig. 4 shows another arrangcnient of de magnetizing winding. as applied to a drum or lap wound machine having four poles, and Fig. 6 such a winding as applied to a similar machine having SlX- poles. l n ithe first case, two poles carry the demagnetizing winding leaving two poles free, and in the second case four poles are arranged to be demagnetized and two left free, the arrangement in each case being such as to produce a symmetrical field.

What I claim is 1. In an electricsupply system, the combination with amultipolar dyiiamohaving a shunt magnetizing winding of a demagnetizing wii'iding arranged on some only of the magnetic poles oil,- the machine, an ac- .'.nn'nilator and means connecting the said accumulator in series with said demagnetizing winding and in parallel with the shunt magnetizing winding, the resistance of the demagnetizing winding in conjunction .with the E. M. ll. of the accumulator being adapted to maintain the required voltage of the dynamo ata. critical or predetermined speed of the dynamo and permit of only a,

small current traversing such winding at such speed and a greater and demagnetizing current when such critical speed is exceeded, for the purpose set ldrth.

2. In an electric supply system, thc coni- 'bination with a work circuit, of a multi polar dynamo having a shunt magnetizing winding on all its poles and a' den'iag'netizing windingon some only of its poles, one end of the latter of the two terminals of the machinebetween which it is desired to maintain a practically constant electromotive' force when the mawinding being connected to one chine is running at or above a predetermined speed, and an accuniulator having one terminal connected to the second end of said demagnetizing winding and to one side of the work circuit and having itsother terminal connected to the second side of the work circult and adapted to be connected to the second terminal. of the machine, the'combined resistance of the demagnetizing winding and the E. M. l of theaccumulator allowing ,only of a small current flowing through said demagnetizing winding when the Voltage of the machine is normal.

3. In an electric supply system, the combination with a work circuit and a multipolardynamo having a nuignetizing winding on all its poles, of a dcu'iagnctizing winding arranged on some only of said. poles and in parallel with the n'iagnetizing winding, an accumulator sin'iultancously supplying the work circuit and acting in opposition to the dynamo through the dcmagnctizing winding, the E. M. F. of the said accumulator combined with the resistance of the demagnetizing winding allowing only a small and practically inoperative current to flow in the said demagnetizingwinding while the normal voltage of the dynamo obtains and a greater and regulating current" when the speed of the machine exceeds the normal, for the purpose settorth.

d. In an electric supply system, the comation with a work circuit and a multir dynamo having a magnetizing windi on all its: poles, of a demagnctizing winding arranged on some only oi? said poles and in parallel with the magnetizing winding, an accumulator connected in circuit with one terminal between the dcmagnctizing winding and one end of one side of the work circuit and with the other terminal between one brush ot' the dynamo and the corresponding end of the other side of the work circuit, so ;l\ to impress a \Ultlgt upon the demagnetizing winding in opposition to the voltage of the dynamo, the resistance of the demagnetizing whaling permitting only a small and practically inoperative current to How through the said winding until the normal spend and voltage of the dynamo is slightly increased when a greater current, acting to dcmagnctizc more or less the poles upon which it placed, will flow through said winding.

.lii an electric supply system, the combination with a work circuit, and a multipolar dynamo having a magnetizing wind- 2 on all ts pol s, of a dcmagnctizing winding on some only of the said poles, an accumnlatin' connected in series with the demagnctizing winding simultaneously supplying the work circuit and acting in oppositioirto the voltage of the dynamo through such dcmagnctizing winding, and a similar accumulator directly connected across the armature of the dynamo to enable it to be charged at the r quired voltage of the machine while the other discharging at a lower rol ige.

(3. in an electric supply system, the comlJlIltll'iUil of a dynamo having magnetizing and demagnetizing windings connected in parallel, the dcmagnctizing winding being on some only of the magnetic poles oi. the machine, a, work circuit one side of which is connected to one terminal of the dynamo through the demagnetizing winding while the other side is arranged to be connected to the other terminal of the dynamo, an accumulator connected to said work circuit and adapted to allow only of the demagnctizing winding being traversed by a small and practically inoperative current while the voltage of the dynamo is normal, a

second accumulator arranged in a separate circuit connected across the terminals of the dynamo and adapted to be charged in said winding being on some only of the magnetic poles of the machine, a work circuit having one side connected with the demagnetizing winding, an accumulator having one terminal connected between the demagnetizing winding and said work circuit and its other terminal connected to the other side of the work circuit and adapted to be connected to the terminal of the dynamo opposite to that to which the demagnetizing winding is connected, an accumulator, similar to the ac cumulator aforesaid, located in a circuit directly supplied by the generator and means for interchanging such accumulators.

8. In an electric supply system, the combination with multipolar shunt wound dy- 30 namo and means for opening the circuit thereof when its speed falls below a given normal speed, of a demagnetizing winding arn nged on some only of the poles of such dynamo and having one end connected it) one of the terminals of the machine, an accumnlator connected to the second end of the demagnetizing winding and means for connecting the said accumulator to the. sccend terminal of the dynamo, a work circuit connected to a point between the demagnetizing winding and accumulator and to the second terminal of the accumulator, a second accumulator connected directly across the terminals of the dynamo, and so means for interchanging the accumulators, substantially as described.

Signed at London England this 20th day oi July 1906.

MATTHEW WILLIAM WALBANK MACKIE.

\Vitnesses:

H. D. Jameson, R. F. \VILLIAMS. 

